Question
Chemistry Question on d -and f -Block Elements
The electronic configurations of Eu (Atomic No. 63), Gd(Atomic No. 64) and Tb (Atomic No. 65) are:
A
[Xe]4f65d16s2,[Xe]4f75d16s2 and [Xe]4f96s2
B
[Xe]4f65d16s2,[Xe]4f75d16s2 and [Xe]4f85d16s2
C
[Xe]4f76s2,[Xe]4f75d16s2 and [Xe]4f96s2
D
[Xe]4f76s2,[Xe]4f86s2 and [Xe]4f85d16s2
Answer
[Xe]4f76s2,[Xe]4f75d16s2 and [Xe]4f96s2
Explanation
Solution
63Eu⇒[Xe]4f75d06s2
64Gd⇒[Xe]4f75d16s2
half filled f subshell is more stable
65Tb⇒[Xe]4f95d06s2